Think corpses and detectives wanting to know how long that body has been in a storage locker or suitcase. It’s the blowfly, of course. Its larvae, a.k.a. maggots, feed on rotting flesh, which could be that spouse or business partner who got in the way. Or, in a good police procedural, both the spouse and the business partner, sent to the great beyond together for their transgressions.

By seeing whether the eggs have hatched and how big the larvae are, forensic scientists can get an idea of how much time has passed since the victims met their end and began the final chapter in the way of all flesh.

By the way, if you have a problem with a spouse or business partner, it’s worth keeping in mind that the flies can indeed get into a suitcase. They stick their ovipositor through the gaps in the zipper. Or the newly hatched larvae themselves can sneak through.

But there are aspects of the maggot’s life that have remained somewhat obscure. Martin Hall, a forensic entomologist at the Natural History Museum in London, thought that one part of the fly’s development in particular needed further study. The maggots are a bit like caterpillars in that at a certain point in their development they wrap themselves up in a case and go through one of the most astonishing events in the natural world: metamorphosis.

In 10 days, the maggot, which has no legs or eyes and is something like “an animated sock,” Dr. Hall said, turns into the extraordinarily complex blowfly. No doubt blowflies are not as appealing as butterflies to most people, but chalk that up to a human bias for pretty fluttery things that land on flowers. It’s certainly not the fly’s fault. Any close-up image of its multifaceted, jewel-like eye shows that it is marvelous in its own way, even if it does feed on the dead.

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Dr. Hall and his colleagues used X-ray video and microscopic CT scans to create a record of those 10 days in more visual detail than ever before, which they reported in the journal Royal Society Open Science.

The report concentrated on a remarkable period of about an hour and a half that occurs about 28 hours into the metamorphosis. In that brief time, the socklike maggot transforms its outer shape into that of the fly, “with head, thorax and abdomen.”

This report is just about the new detail of the fly’s development, and the possibility that the technique could be useful in studying the metamorphoses of other insects inside their hard, opaque cases.

Another paper will follow, Dr. Hall said, on how the visual record will be useful to detectives and others trying to determine when people and animals expired.